检索结果-南通市图书馆

Science China(Technological Sciences) 2019年第1期62卷 39-46页

作者： BAI Kun ZHU Lang yuan mi LEE Kok-Meng State Key Lab of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology Woodruff School of Mechanical Engineering Georgia Institute of Technology

A variable magnetization(VM) motor by incorporating magnets that can be flexibly configured with variable magnetization process is proposed to meet the emerging requirements on motor efficiency and actuator compliance in robotic applications. A generalized spin torque model is established which provides a relationship between the motor torque and two different types of motor inputs, the current inputs and the magnet magnetizations. Avariable magnetization process is proposed based on the study of the hysteresis properties of the magnetic materials and the design criteria for implementing the variable magnetization process with current pulses are established. The feasibility of the variable magnetization is validated with experimental data and the motor functions and performances are numerically demonstrated and evaluated. The results show that the VM motor can maintain high efficiency by switching between two actuation modes. Controllable stiffness at different equilibria can be also achieved with the VM motor with instantaneous magnetizing current pulses.

关键词： compliant actuators direct-drive motors variable stiffness motors variable magnetization motors

Reduction behavior of iron ore powder by high-volatile coal in thermogravimetric-gas chromatographic and kinetic analysis

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第1期31卷 92-107页

作者： Rui-meng Shi Qi-yuan mi Bin Li Xiao Shi Chong Zou Jing Guo Han-jie Guo School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710055ShaanxiChina China International Engineering Consulting Corporation Beijing100048China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing100083China

The reduction behavior of iron ore powder by high-volatile coal was investigated,and its kinetic mechanism was *** effect of volatiles in coal on the reduction reaction of iron ore was compared by utilizing a Xinjiang lignite with a high volatile content and its pyrolysis carbon produced by high-temperature pyrolysis to remove volatiles,serving as a *** mass loss and gas composition of the samples during the reduction process were detected using thermo-gravimetric analysis and gas chromatography,and the morphological changes of iron ore powder were observed through scanning electron *** kinetic parameters of the iron oxide reduction reaction were calculated by the Flynn-Ozawa-Wall method,and the kinetic mechanism of volatile participation in the iron oxide reduction reaction was determined through the Coats-Redfern *** results indicate that the coupling effect between the high-volatile coal pyrolysis and reduction reactions occurs during the second stage of the entire coupling process,which corresponds to the late stage of coal pyrolysis with a substantial release of H_(2)and *** volatiles in coal actively participated in the reduction reaction,reducing the initiation temperature of the reaction by around 200℃.The reduction of iron oxides by high-volatile coal was jointly promoted by the"hydrogen cycle"and"carbon cycle",resulting in a higher reduction extent and metallization rate at the end of the *** high-volatile coal was used as the reductant,the average activation energy for the entire process was 76.5 kJ/mol,a significant decrease compared to the employment of pyrolysis carbon without volatiles as the reductant(1167 kJ/mol).

关键词： Direct reduction High-volatile coal Volatile Kinetics Reduction mechanism

Defect detection in near-surface blind zone using Green’s function reconstruction of diffuse field sector scanning

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Acoustics 2021年第3期40卷 447-459页

作者： WANG Hanlu HE Liyuan mi yuan WU Dawei State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210001

Aiming at the problem of defect detection in the near-surface blind zone of structure,the detection method for reconstruction of Green^function by sector scanning of diffuse field is *** on the theoretical analysis of the Green^function reconstruction of diffuse field sector scanning,a 5 MHz ultrasonic phased array probe is utilized to test the near-surface defects of an aluminum *** factors that affect the imaging results,such as the delay time,time window length and scanning methods,are further *** results show that this method can effectively detect defects from 1.5 mm to 3.0 mm in the near-surface blind zone of the aluminum *** effective diffusion time of the sector scanning method is longer than the full matrix capture method by more than 0.5 *** particularly,within the effective diffusion time,as the receiving delay time and the time window length increase,the imaging quality is *** research work provides an effective and feasible method for ultrasonic detection of defects in the near-surface blind zone.

关键词： function sector delay

Development and validation of machine learning models for nonalcoholic fatty liver disease

在线全文

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2023年第6期22卷 615-621页

作者： Hong-Ye Peng Shao-Jie Duan Liang Pan mi-yuan Wang Jia-Liang Chen Yi-Chong Wang Shu-Kun Yao Graduate School of Beijing University of Chinese Medicine Beijing 100029China Department of Gastroenterology China-Japan Friendship HospitalBeijing 100029China Phase 1 Clinical Trial Center Deyang People’s HospitalDeyang 618000China School of Public Health Tongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China Center of Integrated Traditional Chinese and Western Medicine Beijing Ditan HospitalCapital Medical UniversityBeijing 100102China

Background: Nonalcoholic fatty liver disease(NAFLD) had become the most prevalent liver disease worldwide. Early diagnosis could effectively reduce NAFLD-related morbidity and mortality. This study aimed to combine the risk factors to develop and validate a novel model for predicting NAFLD. Methods: We enrolled 578 participants completing abdominal ultrasound into the training set. The least absolute shrinkage and selection operator(LASSO) regression combined with random forest(RF) was conducted to screen significant predictors for NAFLD risk. Five machine learning models including logistic regression(LR), RF, extreme gradient boosting(XGBoost), gradient boosting machine(GBM), and support vector machine(SVM) were developed. To further improve model performance, we conducted hyperparameter tuning with train function in Python package ‘sklearn’. We included 131 participants completing magnetic resonance imaging into the testing set for external validation. Results: There were 329 participants with NAFLD and 249 without in the training set, while 96 with NAFLD and 35 without were in the testing set. Visceral adiposity index, abdominal circumference, body mass index, alanine aminotransferase(ALT), ALT/AST(aspartate aminotransferase), age, high-density lipoprotein cholesterol(HDL-C) and elevated triglyceride(TG) were important predictors for NAFLD risk. The area under curve(AUC) of LR, RF, XGBoost, GBM, SVM were 0.915 [95% confidence interval(CI): 0.886–0.937], 0.907(95% CI: 0.856–0.938), 0.928(95% CI: 0.873–0.944), 0.924(95% CI: 0.875–0.939), and 0.900(95% CI: 0.883–0.913), respectively. XGBoost model presented the best predictive performance, and its AUC was enhanced to 0.938(95% CI: 0.870–0.950) with further parameter tuning. Conclusions: This study developed and validated five novel machine learning models for NAFLD prediction, among which XGBoost presented the best performance and was considered a reliable reference for early identification of high-risk patients wit

关键词： Nonalcoholic fatty liver disease Machine learning Predictive factors

在线全文

学校读者我要写书评

暂无评论

古印度那烂陀寺教育管窥

世界宗教文化 2023年第2期 174-181页

作者：米媛中国社会科学院哲学研究所

那烂陀寺是古印度在佛教文化教育方面的一个成功范例。印度佛教从起源到衰落都与那烂陀寺密切相关,它是研究佛教及印度各种学问的重要教育中心。那烂陀寺的学术代表着当时印度文化的最高水平,并广泛传播至亚洲多个国家。如今虽然业已衰... 详细信息

那烂陀寺是古印度在佛教文化教育方面的一个成功范例。印度佛教从起源到衰落都与那烂陀寺密切相关,它是研究佛教及印度各种学问的重要教育中心。那烂陀寺的学术代表着当时印度文化的最高水平,并广泛传播至亚洲多个国家。如今虽然业已衰落,但该寺曾经培养出众多学识渊博、德才兼备的学者和思想家,其在教育方面的宝贵经验对今天仍有借鉴意义。

关键词：那烂陀寺佛教教育古印度

在线全文

学校读者我要写书评

暂无评论

一种简单的溶剂热法合成炭微球(英文)

新型炭材料 2009年第4期24卷 375-378页

作者：米远祝刘应亮长江大学化学与环境工程学院湖北荆州434023 暨南大学化学系广东广州510632

利用一种简单的溶剂法合成炭微球。采用无水乙醇作为碳源和溶剂,以无水乙醇还原Ni(Ac)2得到的Ni作为催化剂,最佳反应条件:温度500℃、时间48h。采用X-射线衍射仪(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)以及Raman光谱对样品的... 详细信息

利用一种简单的溶剂法合成炭微球。采用无水乙醇作为碳源和溶剂,以无水乙醇还原Ni(Ac)2得到的Ni作为催化剂,最佳反应条件:温度500℃、时间48h。采用X-射线衍射仪(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)以及Raman光谱对样品的成分、晶体结构和形貌进行了分析。结果表明:产品为圆球形和纺锤形两种形貌的炭微球,圆球形炭微球直径为1μm～2μm,纺锤形炭微球直径为1μm～2μm,长度为3μm～6μm。此法简便易行,炭微球的产率高达95%以上,且具有较规则的形貌和窄的尺寸分布。

关键词：溶剂热法炭微球合成

大规模定制产品族设计方案多维物元关联评价研究

在线全文

学校读者我要写书评

暂无评论

计算机集成制造系统 2006年第7期12卷 1146-1152页

作者：单汨源李果陈丹湖南大学工商管理学院

为评价和改进产品族设计方案,在分析和归纳产品族设计概念和流程的基础上,构建了产品族设计方案评价指标体系,并根据定性指标和定量指标的特点,结合层次分析法和物元分析理论,采用多维物元关联模型对产品族设计方案进行评价。最后,以一... 详细信息

为评价和改进产品族设计方案,在分析和归纳产品族设计概念和流程的基础上,构建了产品族设计方案评价指标体系,并根据定性指标和定量指标的特点,结合层次分析法和物元分析理论,采用多维物元关联模型对产品族设计方案进行评价。最后,以一家脚轮生产企业为例进行验证,说明该方法不仅能评价产品族设计方案的综合水平,还能找出评价指标的优势和劣势,具有一定的现实意义。

关键词：大规模定制产品族设计评价指标体系物元关联评价

基于模糊聚类最大树算法的高层建筑基坑工程风险识别方法

在线全文

学校读者我要写书评

暂无评论

吉林大学学报（工学版） 2022年第12期52卷 2892-2897页

作者：廖汉超单汨源湖南大学工商管理学院长沙410082

针对基坑工程勘察局限性和工程临时性等实质问题,提出了基于模糊聚类最大树算法的高层建筑基坑工程风险识别方法。通过绝对值减数法建立了模糊相似矩阵,标准化处理风险指标数据,使用风险评价指数划分基坑施工风险等级。利用模糊聚类定... 详细信息

针对基坑工程勘察局限性和工程临时性等实质问题,提出了基于模糊聚类最大树算法的高层建筑基坑工程风险识别方法。通过绝对值减数法建立了模糊相似矩阵,标准化处理风险指标数据,使用风险评价指数划分基坑施工风险等级。利用模糊聚类定量计算影响元素之间的耦合关系,运用无向连通赋权图形式描述最大树结构,通过连接树结构内互相连通的顶点实现风险识别。仿真结果证明:本文方法能够在判定基坑工程风险等级的同时,准确描述风险的具体位置,识别正确率和效率均可达到预期要求,鲁棒性强。

关键词：基坑施工模糊聚类最大树算法风险识别评价指标

在线全文

学校读者我要写书评

暂无评论

神经系统编码时间节律信息的机制

中国药理学与毒理学杂志 2017年第11期31卷 1120-1126页

作者：弭元元胡岗吴思军事医学研究院军事认知与脑科学研究所北京100850 北京师范大学物理学系北京100875 北京师范大学认知神经科学与学习国家重点实验室北京100875

时间节律信息的提取和编码极其重要,是人们识别语音、欣赏音乐和产生节律运动等的基础。但人们对神经系统提取和处理外部输入中时间节律信息的机制迄今还知之甚少。本课题组提出了一个具有无标度拓扑结构的神经网络模型,并考虑通过神经... 详细信息

时间节律信息的提取和编码极其重要,是人们识别语音、欣赏音乐和产生节律运动等的基础。但人们对神经系统提取和处理外部输入中时间节律信息的机制迄今还知之甚少。本课题组提出了一个具有无标度拓扑结构的神经网络模型,并考虑通过神经元之间的电突触或连接效率随突触连接而减弱的化学突触,来实现枢纽神经元难以被激活等特性。在该模型中,枢纽神经元能触发网络的同步化发放,连接度相对较低的神经元形成的环路决定了同步发放的周期,且枢纽神经元难以被激活的特性避免了网络的爆炸性发放。该模型很好地再现了实验中观察到的长时程周期性同步发放现象,证明神经系统能通过局部网络动力学分布式地处理时序信息。本综述旨在对神经系统编码时间节律信息的机制进行阐述和总结。

关键词：神经网络模型长时程节律信息同步发放神经信息表达

在线全文

学校读者我要写书评

暂无评论

板坯连铸结晶器非正弦振动技术的应用

炼钢 2006年第3期22卷 6-9页

作者：米源武汉钢铁(集团)公司第三炼钢厂湖北武汉430083

介绍了武钢三炼钢的结晶器液压正弦/非正弦振动技术,对非正弦振动与正弦振动的特点进行了比较。对VAI提供的振动参数之间的关系进行了研究和优化调整,降低负滑脱时间,明显减少了振痕深度和改善了铸坯表面质量,同时增加正滑脱时间,降低... 详细信息

介绍了武钢三炼钢的结晶器液压正弦/非正弦振动技术,对非正弦振动与正弦振动的特点进行了比较。对VAI提供的振动参数之间的关系进行了研究和优化调整,降低负滑脱时间,明显减少了振痕深度和改善了铸坯表面质量,同时增加正滑脱时间,降低了粘连漏钢的风险,提高了操作安全性。

关键词：非正弦振动参数优化铸坯表面质量